Sulfadimidine is widely used for the treatment of coccidiosis in
laying hens at the dose of 2 gl-1 for 6 consecutive days via the drinking
water. As a result, there is concern that the residues of this drug may be
retained in the eggs and present a potential risk to human health.
The aim of our study was to determine the residue concentrations
of sulfadimidine in whole eggs of laying hens during and after its oral
administration up to the 15th day of the withdrawal period. The
sulfadimidine residues were determined by a gradient highperformance
liquid chromatography system with a photo-diode array
detector at 275 nm. Our results indicate that the oral administration of
sulfadimidine to laying hens produced a rapid and sustained increase
in sulfadimidine residues in their eggs. The highest residue
concentrations of sulfadimidine were found on the 6th day of
administration. After withdrawal, the residues declined rapidly, but they
were still detectable on the 10th day of the withdrawal period. On day 11,
the residues were below the established MRL (0.1 mgkg-1). The limit of
quantification (LOQ) for sulfadimidine was 0.3 mgkg-1, the detection
limit (LOD) was 0.09 mgkg-1, and the recovery ranged from 91 to 98 %.